This invention relates generally to treatment of film such as photographic film, and more particularly concerns removal of dust from film strip surfaces as well as elimination of static on said surfaces.
Printing speeds have been enormously increased during the last few years. This is particularly true of printing photographic images on photographic paper. The older printers require that a negative be manually placed in a printing "gate". This older method is rapidly being displaced in the printing of amateur films. For example, the strips of customer film can now be spliced into long rolls and then printed automatically on machines that are operated by computers. Speeds have correspondingly increased from a few dozen prints to thousands of prints per hour, made automatically.
Further, the use of small negative film formats like the 35 MM and even 110 has increased manyfold, and laboratories are now making large blowups from very small negatives. However, the increased printing speed greatly enhances the amount of static generated on the film and therefore the amount of dust that is attracted to the film surface. Such dust particles are particularly troublesome on small negatives being used to produce large size prints. Static generated on the film tends to hold the dust or to reattract the dust whenever it is physically wiped off. This has resulted in the need for much reprinting in high speed production laboratories. It has been found that film can be cleaned by blowing a jet of compressed air across the film. In some cases this air has been exposed to a nuclear pellet to cause ionization of the air. When the air around the negative film is ionized, the static bleeds off into the surrounding atmosphere and makes the dust easier to remove. However, this is a passive system depending on the static to bleed off into the air, which is less than satisfactory. Furthermore, the nuclear pellets decay to half their strength every 138.4 days and therefore by the end of the year, when they are picked up for replacement, their effectiveness is but a fraction of their original strength.